Began work on a scene graph merging function.

niflib.cpp

@@ -693,6 +693,101 @@ unsigned int BlocksInMemory() {
 	return blocks_in_memory;
 }
 
+void MapParentNodeNames( map<string,blk_ref> & name_map, blk_ref par ) {
+	//Check if this block is a scene graph node
+	if ( par->QueryInterface( ID_NODE ) == false ) {
+		throw runtime_error( "Only trees that have a node as the root can be merged." );
+	}
+
+	//Check if this is a parent node
+	attr_ref children = par->GetAttr("Children");
+	if ( children.is_null() == true ) {
+		//We are only interested in parent nodes
+		return;
+	}
+
+	//Add the par node to the map, and then call this function for each of its children
+	name_map[par->GetAttr("Name")->asString()] = par;
+
+	list<blk_ref> links = par->GetAttr("Children")->asLinkList();;
+	for (list <blk_ref>::iterator it = links.begin(); it != links.end(); ++it) {
+		if ( it->is_null() == false ) {
+			MapParentNodeNames( name_map, *it );
+		};
+	};
+}
+
+//This function will merge two scene graphs by attatching new objects to the correct position
+//on the existing scene graph.  In other words, it deals only with adding new nodes, not altering
+//existing nodes by changing their data or attatched properties
+void MergeSceneGraph( map<string,blk_ref> & name_map, const blk_ref & root, blk_ref par ) {
+	//Check if this block is a scene graph node
+	if ( par->QueryInterface( ID_NODE ) == false ) {
+		throw runtime_error( "Only trees that have a node as the root can be merged." );
+	}
+	
+	//Check if this block's name exists in the block map
+	string name = par->GetAttr("Name")->asString();
+
+	if ( name_map.find(name) != name_map.end() ) {
+		//This block already exists in the original file, so continue on to its children
+
+		list<blk_ref> links = par->GetAttr("Children")->asLinkList();;
+		for (list <blk_ref>::iterator it = links.begin(); it != links.end(); ++it) {
+			if ( it->is_null() == false ) {
+				MergeSceneGraph( name_map, root, *it );
+			};
+		};
+		return;
+	}
+
+	//This block has a new name and either it has no parent or its parent has a name that is
+	// in the list.  Attatch it to the block with the same name as its parent
+	//all child blocks will follow along.
+	blk_ref par_par = par->GetParent();
+
+	if ( par_par.is_null() == true ) {
+		//This block has a new name and no parents.  That means it is the root block
+		//of a disimilar Nif file.
+		attr_ref par_children = par->GetAttr("Children");
+		
+		//Get the current root child list
+		attr_ref root_children = root->GetAttr("Children");
+			
+		if ( par_children.is_null() == true ) {
+			//This is not a ParentNode class, so simply add it as a new child of the
+			//target root node
+			root_children->AddLink( par );
+		} else {
+			//This is a ParentNode class, so merge its child list with that of the root
+			root_children->AddLinks( par->GetAttr("Children")->asLinkList() );
+		}
+	} else {
+		//This block has a new name and has a parent with a name that already exists.
+		//Attatch it to the block in the target tree that matches the name of its
+		//parent
+
+		//Get the block to attatch to
+		blk_ref attatch = name_map[par_par->GetAttr("Name")->asString()];
+
+		//Add this block as new child
+		attatch->GetAttr("Children")->AddLink( par );
+	}
+}
+
+void MergeNifTrees( blk_ref target, blk_ref right ) {
+	//For now assume that both are normal Nif trees just to verify that it works
+
+	//Create a list of names in the target
+	map<string,blk_ref> name_map;
+	MapParentNodeNames( name_map, target );
+
+	//Use the name map to merge the Scene Graphs
+	MergeSceneGraph( name_map, target, right );
+}
+
+
+
 //--Attribute Reference Functions--//
 
 attr_ref::operator blk_ref() const { return _attr->asLink(); }

niflib.h

@@ -314,6 +314,14 @@ blk_ref ReadNifTree( istream & in );
  */
 void WriteNifTree( string const & file_name, blk_ref const & root_block, unsigned int version = VER_4_0_0_2 );
 
+
+/*!
+ * Merges two Nif trees into one.  For standard Nif files, any blocks with the same name are merged.  For Kf files, blocks are attatched to those that match the name specified in the KF root block.
+ * \param root1 The root block of the first Nif tree to merge.
+ * \param root2 The root block of the second Nif tree to merge.
+ */
+void MergeNifTrees( blk_ref root1, blk_ref root2 );
+
 //// Returns list of all blocks in the tree rooted by root block.
 //list<blk_ref> GetNifTree( blk_ref const & root_block );